A wireless device (e.g., a cellular phone or a smartphone) in a wireless communication system may transmit and receive data for two-way communication. The wireless device may include a transmitter for data transmission and a receiver for data reception. For data transmission, the transmitter may modulate a radio frequency (RF) carrier signal with data to generate a modulated RF signal, amplify the modulated RF signal to generate a transmit RF signal having the proper output power level, and transmit the transmit RF signal via an antenna to another device such as, for example, a base station. For data reception, the receiver may obtain a received RF signal via the antenna and may amplify and process the received RF signal to recover data sent by the other device.
The wireless device may operate within multiple frequency bands. For example, the wireless device may transmit and/or receive an RF signal within a first frequency band and/or within a second frequency band. In many cases, an antenna design for the wireless device may depend on the frequency band used during operation. Different frequency bands (having different associated wavelengths) often dictate different antenna sizes. For example, a length of an antenna element may be selected to be a wavelength multiple (λ/4, λ/2 etc.) of the RF signal. Thus, an antenna designed for use within the first frequency band may have a different antenna element length compared to an antenna designed for use within the second frequency band. Using separate antennas for each frequency band may increase the size, cost, and/or complexity of the wireless device.
Thus, there is a need to reduce the number of antennas and/or size of antennas used by wireless devices that operate within multiple frequency bands.